It is narrated from Sayyiduna Ali (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) used to perform rukū‘ (bowing) in such a manner that if a bowl filled with water were placed on the Prophet’s (peace and blessings be upon him) back, it would not fall.
Hadith Referenceمسند احمد / مسند الخلفاء الراشدين / 997
Hadith Gradingحکم دارالسلام:إسناده ضعيف لجهالة الشيخ الذى روى عنه أحمد، ولضعف سنان بن هارون